Re: Air brakes on this bus...
where i live in michigan, there are neighboring school districts that have identical buses, except for brakes. One district has almost exclusively air brakes, while the other district has all hydraulic. Like the above poster said, it's all about what the district chose when they ordered their buses. I think that either system works great in a skoolie. Air brakes are nice from a standpoint that you can use the air for other things, like filling tires, running air tools, inflating air mattresses, opening doors etc. Hydraulic brakes are nice because you can just turn the key and go, and it's easier for "anyone" to drive, and they don't require you to manually adjust the brakes on a regular basis or really have an understanding of how they work. If you have air brakes, you really should have a good understanding of how the system works, and be able to check and adjust your brakes regularly, especially if driving through the mountains. When in the mountains and you read a sigh that says "drivers check brakes" they mean you should stop your vehicle, get out, crawl under neath with a 9/16 wrench and physically check your brakes. new trucks come with automatic slack adjusters, which on vehicles that don't get used often tend to be a PITA because they freeze up which makes them stop automatically adjusting, and many of them cannot be manually adjusted.
I prefer air brakes, but drove a skoolie through the mountains more than a few times with hydraulic, and once was even grossly overloaded pulling a trailer and still found the hydro's to be adequate.
Quis custodiet ipsos custodes (who will watch the watchmen?)